<?php 

/**
 * Helper class for accessing information about modules.
 *
 * @author Olav Morken, UNINETT AS.
 * @package simpleSAMLphp
 * @version $Id$
 */
class SimpleSAML_Module {


	/**
	 * Retrieve the base directory for a module.
	 *
	 * The returned path name will be an absoulte path.
	 *
	 * @param string $module  Name of the module
	 * @return string  The base directory of a module.
	 */
	public static function getModuleDir($module) {
		$baseDir = dirname(dirname(dirname(__FILE__))) . '/modules';
		$moduleDir = $baseDir . '/' . $module;

		return $moduleDir;
	}


	/**
	 * Determine whether a module is enabled.
	 *
	 * Will return FALSE if the given module doesn't exists.
	 *
	 * @param string $module  Name of the module
	 * @return bool  TRUE if the given module is enabled, FALSE if not.
	 */
	public static function isModuleEnabled($module) {

		$moduleDir = self::getModuleDir($module);

		if(!is_dir($moduleDir)) {
			return FALSE;
		}

		if (assert_options(ASSERT_ACTIVE) && !file_exists($moduleDir . '/default-enable') && !file_exists($moduleDir . '/default-disable')) {
			SimpleSAML_Logger::error("Missing default-enable or default-disable file for the module $module");
		}

		if(file_exists($moduleDir . '/enable')) {
			return TRUE;
		}

		if(!file_exists($moduleDir . '/disable') && file_exists($moduleDir . '/default-enable')) {
			return TRUE;
		}

		return FALSE;
	}


	/**
	 * Get available modules.
	 *
	 * @return array  One string for each module.
	 */
	public static function getModules() {

		$path = self::getModuleDir('.');

		$dh = opendir($path);
		if($dh === FALSE) {
			throw new Exception('Unable to open module directory "' . $path . '".');
		}

		$modules = array();

		while( ($f = readdir($dh)) !== FALSE) {
			if($f[0] === '.') {
				continue;
			}

			if(!is_dir($path . '/' . $f)) {
				continue;
			}

			$modules[] = $f;
		}

		closedir($dh);

		return $modules;
	}


	/**
	 * Resolve module class.
	 *
	 * This function takes a string on the form "<module>:<class>" and converts it to a class
	 * name. It can also check that the given class is a subclass of a specific class. The
	 * resolved classname will be "sspmod_<module>_<$type>_<class>.
	 *
	 * It is also possible to specify a full classname instead of <module>:<class>.
	 *
	 * An exception will be thrown if the class can't be resolved.
	 *
	 * @param string $id  The string we should resolve.
	 * @param string $type  The type of the class.
	 * @param string|NULL $subclass  The class should be a subclass of this class. Optional.
	 * @return string  The classname.
	 */
	public static function resolveClass($id, $type, $subclass = NULL) {
		assert('is_string($id)');
		assert('is_string($type)');
		assert('is_string($subclass) || is_null($subclass)');

		$tmp = explode(':', $id, 2);
		if (count($tmp) === 1) {
			$className = $tmp[0];
		} else {
			$className = 'sspmod_' . $tmp[0] . '_' . $type . '_' . $tmp[1];
		}

		if (!class_exists($className)) {
			throw new Exception('Could not resolve \'' . $id .
				'\': No class named \'' . $className . '\'.');
		} elseif ($subclass !== NULL && !is_subclass_of($className, $subclass)) {
			throw new Exception('Could not resolve \'' . $id . '\': The class \'' .
				$className . '\' isn\'t a subclass of \'' . $subclass . '\'.');
		}

		return $className;
	}


	/**
	 * Get absolute URL to a specified module resource.
	 *
	 * This function creates an absolute URL to a resource stored under ".../modules/<module>/www/".
	 *
	 * @param string $resource  Resource path, on the form "<module name>/<resource>"
	 * @param array $parameters  Extra parameters which should be added to the URL. Optional.
	 * @return string  The absolute URL to the given resource.
	 */
	public static function getModuleURL($resource, array $parameters = array()) {
		assert('is_string($resource)');
		assert('$resource[0] !== "/"');

		$url = SimpleSAML_Utilities::getBaseURL() . 'module.php/' . $resource;
		if (!empty($parameters)) {
			$url = SimpleSAML_Utilities::addURLparameter($url, $parameters);
		}
		return $url;
	}


	/**
	 * Call a hook in all enabled modules.
	 *
	 * This function iterates over all enabled modules and calls a hook in each module.
	 *
	 * @param string $hook  The name of the hook.
	 * @param mixed &$data  The data which should be passed to each hook. Will be passed as a reference.
	 */
	public static function callHooks($hook, &$data = NULL) {
		assert('is_string($hook)');

		$modules = self::getModules();
		sort($modules);
		foreach ($modules as $module) {
			if (!self::isModuleEnabled($module)) {
				continue;
			}

			$hookfile = self::getModuleDir($module) . '/hooks/hook_' . $hook . '.php';
			if (!file_exists($hookfile)) {
				continue;
			}

			require_once($hookfile);

			$hookfunc = $module . '_hook_' . $hook;
			assert('is_callable($hookfunc)');

			$hookfunc($data);
		}
	}

}

?>